青藏高原东南部楚雄盆地构造-热演化史及其与油气关系

青藏高原东南部是构造最为活跃、变形最强烈的地区之一.楚雄盆地作为青藏高原东南部重要的中生代含油气叠合盆地，其演化历史复杂，后期改造强烈，热演化史研究薄弱.恢复楚雄盆地构造-热演化史对系统评价盆地油气资源和深入认识青藏高原东南部的构造变形过程有重要意义.本文研究在楚雄盆地全盆地系统采集了裂变径迹样品，分析确定了盆地的抬升过程，结合大量镜质体反射率（R_O）、包裹体测温等古温标，系统恢复了楚雄盆地构造-热演化史.裂变径迹研究结果表明楚雄断裂以西靠近哀牢山—红河断裂带地区的冷却年龄在41.9~72.7 Ma之间，主要为始新世41.9~55.5 Ma；楚雄断裂以东冷却年龄在20.0~38.4 Ma之间，主要为渐新世-早中新世.楚雄盆地抬升过程总体具有西早东晚的特征，主体部位20~38.4 Ma以来有一次快速抬升冷却过程.楚雄盆地三叠系热演化程度高，R_O异常高值与火成岩活动密切相关.热演化史研究表明三叠系最大古地温在上新世之前达到，最高古地温梯度可达30℃·km^-1.三叠系烃源岩在侏罗纪开始生烃，白垩纪为主要生烃期，古新世-始新世主要为过成熟生干气阶段.渐新世以来盆地整体抬升，地层温度降低，生烃作用减弱.楚雄盆地构造-热演化史除了受火成岩影响外，还与印度和欧亚板块的碰撞及哀牢山—红河断裂带的活动密切相关.

Tectono-thermal evolution and its relationship with petroleum generation in the Chuxiong Basin,southeastern Tibetan Plateau

The southeastern Tibetan Plateau is one of the most tectonically active and rapidly deforming regions of continental crust in the world. Chuxiong Basin is an important Mesozoic petroliferous superimposed basin in the southeastern Tibetan Plateau, which has experienced complex evolution history and strong later transformations. However, the tectono-thermal evolution has not been well evaluated. The reconstruction of the tectono-thermal evolution history in the Chuxiong Basin is of significant important for evaluating its potential for oil and gas exploration and understanding the tectonic deformation process of the southeastern Tibetan Plateau. In this study, we systemically collected the fission track samples from the entire Chuxiong Basin and studied the uplift process of the basin. Combined with the measurement of vitrinite reflectance and inclusion homogenization temperature, we systematically reconstructed the tectono-thermal evolution of the Chuxiong Basin. The results show that the fission track cooling ages close to the Ailaoshan-Red River Fault Zone range from 41.9 Ma to 72.7 Ma in the west of the Chuxiong Fault, mainly belong to Eocene with ages range from 41.9 Ma to 55.5 Ma. The fission track cooling ages in the east of the Chuxiong Fault range from 20.0 Ma to 38.4 Ma, mainly belong to Oligocene-Early Miocene. We suggest the western part of the basin was lifted in the Eocene followed by the uplift of the eastern part in the Oligocene-Early Miocene, which was characterized by early west and late east. The main part of the basin experienced a rapid uplift cooling process since 20~38.4 Ma. The Triassic strata experienced a high degree of thermal evolution, and their abnormal high vitrinite reflectance values are closely related to igneous rock activity. The modeled thermal evolution shows that the maximum paleotemperature for the Triassic strata was reached before the Pliocene, and the maximum paleotemperature gradient reached up to 30℃·km-1. The Triassic hydrocarbon source rocks began to generate hydrocarbons in the Jurassic, and the main hydrocarbon generation peaked in the Cretaceous. The hydrocarbon source rock reached over-mature dry gas generation stage during the Paleocene-Eocene period, and experienced reduced hydrocarbon generation since the Oligocene coupled with the uplift and cooling of the basin. The tectono-thermal evolution of the Chuxiong Basin is closely related to the igneous rock activity, the collision of the Indian and Eurasian plates and the activities of the Ailaoshan-Red River Fault Zone.